NAME

Class::Bits - Class wrappers around bit vectors

SYNOPSIS

  package MyClass;
  use Class::Bits;

  make_bits( a => 4,  # 0..15
             b => 1,  # 0..1
             c => 1,  # 0..1
             d => 2,  # 0..3
             e => s4  # -8..7
             f => s1  # -1..0
   );

   package;

   $o=MyClass->new(a=>12, d=>2);
   print "o->b is ", $o->b, "\n";

   print "bit vector is ", unpack("h*", $$o), "\n";

   $o2=$o->new();
   $o3=MyClass->new($string);

ABSTRACT

Class::Bits creates class wrappers around bit vectors.

DESCRIPTION

Class::Bits defines classes using bit vectors as storage.

Object attributes are stored in bit fields inside the bit vector. Bit field sizes have to be powers of 2 (1, 2, 4, 8, 16 or 32).

There is a class constructor subroutine:

make_bits( field1 => size1, field2 => size2, ...)

exports in the calling package a ctor, accessor methods, some utility methods and some constants:

Sizes can be prefixed by s or u to define signedness of the field. Default is unsigned.

$class->new()

creates a new object with all zeros.

$class->new($bitvector)

creates a new object over $bitvector.

$class->new(%fields)

creates a new object and initializes its fields with the values in %fields.

$obj->new()

clones an object.

$obj->$field()

$obj->$field($value)

gets or sets the value of the bit field $field inside the bit vector.

$class->length

$obj->lenght

returns the size in bits of the bit vector used for storage.

$class->keys

$obj->keys

returns an array with the names of the object attributes

$obj->as_hash

returns a flatten hash with the object attributes, i.e.:

  my %values=$obj->as_hash;

%INDEX

hash with offsets as used by vec perl operator (to get an offset in bits, the value has to be multiplied by the corresponding bit field size).

%SIZES

hash with bit field sizes in bits.

%SIGNED

hash with signedness of the fields

Bit fields are packed in the bit vector in the order specified as arguments to make_bits.

Bit fields are padded inside the bit vector, i.e. a class created like

  make_bits(A=>1, B=>2, C=>1, D=>4, E=>8, F=>16);

will have the layout

  AxBBCxxx DDDDxxxx EEEEEEEE xxxxxxxx FFFFFFFF FFFFFFFF

EXPORT

make_bits

SEE ALSO

"vec" in perlfunc, Class::Struct

AUTHOR

Salvador Fandiño, <sfandino@yahoo.com>

COPYRIGHT AND LICENSE

Copyright 2003 by Salvador Fandiño

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.